Albumin is a small protein (66.3 kDa) and the most abundant in human plasma, representing 55-65% of the total protein mass. It has different biological functions, such as the maintenance of osmotic pressure between the vascular and extravascular spaces, and the transport and storage of a wide variety of products (ions, hormones, medications, bilirubin, etc.) and, when catabolized, may serve as an endogenous source of amino acids.
Hyperalbuminuria is observed only in case of acute dehydration.
Hypoalbuminuria can be caused by a decrease in synthesis or by increased catabolism, or a combination of both factors. It is related to numerous malfunctions: congenital analbuminaemia, inflammatory disorders, hepatic diseases, malnutrition, oedema and ascites, etc. Severe hypoalbuminemia causes a serious imbalance in the osmotic pressure between the vascular and extravascular spaces, leading to oedema.